DNA markers to help track humans' movement across the globe

In the nick of time -- in terms of human history, anyway -- the National Geographic Society and IBM have announced a five year project that will use DNA markers to retrace the epic colonisation of Earth by modern human beings.

The Genographic Project will collect DNA samples from at least 100,000 volunteers, including indigenous populations and the general public, to develop a detailed picture of patterns of human migration around the world since the first small bands of modern humans began leaving their African homeland 60,000 to 100,000 years ago.

The Genographic Project will use sophisticated computer algorithms to sift data from the world's largest collection of DNA samples from living humans, and from ancient human remains.

La Trobe University geneticist Dr Robert Mitchell, who will lead the Australian segment of the project, said the Australian data was likely to be integral to resolving patterns of some of the earliest human migrations out of Africa, as well as establishing the ancestry of Australia's Aborigines and their relationships with the other peoples of the world.

The project is being headed by brilliant young US geneticist, author and TV documentary maker Dr Spencer Wells, a protege of eminent Stanford University human geneticist Prof Luigi Luca Cavalli-Sforza.

Wells, a scientific prodigy who was only 16 when he was accepted as a student at the University of Texas, became an international celebrity after publishing a book and making an associated TV documentary, both titled 'The Human Journey', in 2002.

'The Human Journey' recorded Wells' journeys around the world collecting blood samples from males from indigenous groups, to analyse DNA markers on the Y chromosome, which is transmitted unchanged, except for sporadic mutations, through the paternal line.

Wells' book described, among other things, how many male Australian Aborigines carry an ancient Y-chromosome marker called M130, the first novel marker to arise after humans left East Africa some 60,000 years ago. The marker supports archaeological evidence for Australia's early colonisation by seagoing people soon after the African diaspora began some 60,000 years ago.

In the early 1990s, Cavalli-Sforza initiated a similar project, the Human Genome Diversity Project, but it was brought undone when activist groups alleged that Western scientists planned to appropriate and patent unusual genes uncovered by the project.

Mitchell said the new Genographic Project was very carefully designed to avoid creating controversy or apprehension among ethnic groups or members of the public contributing to the DNA database.

"Anything we sample -- blood, saliva or cheek scrapings -- will stay in Australia, and will only be sampled and tested for the DNA markers being used," he said. "They are all neutral genetic markers -- not genes. They have no value except to anthropologists.

"They will provide no information about the disease status or genetic health of the individuals, and they will be used for no other purpose than the Genographic Project. All the results will be stored in the world database, and they will be anonymous."

Mitchell, who has been using DNA markers to study the prehistory of Tasmania's Aborigines, said the new study aimed to determine the timing and route of human migrations, ancient and modern, and to establish ancestral relationships between human groups, using a combination of genetic and linguistic evidence.

He said he expected the project would reveal some minor genetic differentiation between Aboriginal groups in Australia, based on ecological zoning and relatively recent contact between coastal peoples and seafaring visitors to Australia's north.

It was already known that, in addition to M130, at least two other major Y-chromosome markers were common in male Aborigines.

But he said the overall genetic diversity in Australia was likely to be smaller that might be expected from the continent's 60,000-year history of migration, and evolution in isolation.

"I expect the study to reinforce the oneness of the Aborigines as an indigenous people, and allay some ideas about them being culturally isolated groups," he said.

"Two things are really intriguing. One is to determine how Australia was settled so early, and whether we can accurately time the colonisation from the genetics.

"The other is that, while we can trace the genetic legacy of Genghis Khan all the way from China to Egypt, we're finding it very hard to trace the earliest ancestors of the Aborigines. Have they all disappeared, or will we find some connections with early groups in Asia?"

Former ANU human geneticist Prof Sue Serjeantson, now with the Australian Academy of Science, said previous studies of human migrations of the Pacific had shown that the Polynesians, who colonised the entire Pacific, descended ultimately from a hill people in Taiwan, whereas the seafaring Micronesians were descended from hill tribes in the Philippines.

Serjeantson said her early studies on differentiation of human leucocyte antigens (HLA) types in Australian Aboriginal groups had shown that there were virtually no shared HLA alleles between groups living in WA's Kimberley region, and Queensland's Cape York Peninsula, suggesting long genetic isolation.